One boy
0
I'm trying to print the column name in a new column 'result' if the 'b' or 'c' match (equal) 'a' for every row.
This is an example, I have more than 10 column names.
my df is like this:
a b c
a 0 1 2
b 4 4 5
c 6 7 6
d 9 9 11
expected result:
a b c result
a 0 1 2 NaN
b 4 4 5 b
c 6 7 6 c
d 9 9 11 b
Use idxmax on the comparison of b/c and a (with eq).
Also use a mask (with where) to ensure there is at least one valid match as idxmax would return the first False index if no True is found:
m = df[['b', 'c']].eq(df['a'], axis=0)
df['result'] = m.idxmax(1).where(m.any(1))
output:
a b c result
a 0 1 2 NaN
b 4 4 5 b
c 6 7 6 c
d 9 9 11 b
intermediate m:
b c
a False False
b True False
c False True
d True False